At the outset of a drilling operation, drillers typically establish a drill plan that includes a target location and a drilling path to the target location. Once drilling commences, the bottom hole assembly (BHA) may be directed or “steered” from a vertical drilling path in any number of directions, to follow the proposed drill plan. For example, to recover an underground hydrocarbon deposit, a drill plan might include a vertical bore to a side of a reservoir containing the deposit, then a directional or horizontal bore that penetrates the deposit. The operator may then follow the plan by steering the BHA through the vertical and horizontal aspects in accordance with the plan. Drill plans may be chosen to minimize the time required to drill a wellbore and/or to access the largest amounts of oil or gas possible.
Drilling operations in horizontal or near-horizontal wellbores pose additional challenges for drillers. For example, accessing a deposit may require that a driller drill multiple horizontal wellbores in close proximity. In this case, the tolerances for drilling each wellbore may be very small, and may require a high level of expertise as well as disciplined navigation to avoid making costly mistakes. Even minor inaccuracies in measurement or steering can cause problems for the current drilling operation as well as successive operations.
Furthermore, data received during a drilling operation may signal that changes are needed in the drill plan, such as to direct the BHA to a more productive area. These changes may be difficult for a driller to implement because they are not planned at the outset of the drilling operation and may present mathematical challenges to correctly maneuver the BHA according to the required changes.
Thus, a more efficient, reliable, and intuitive method for steering a BHA, visualizing drilling tolerances, and making changes in a drill plan is needed.